Vanguard Portfolio Management (OTTR) holds 2.96M shares, 7.06% stake

Rhea-AI Filing Summary

Vanguard Portfolio Management reports beneficial ownership of 2,963,293 shares of Otter Tail Corp common stock, equal to 7.06% of the class as reported for the period ended 03/31/2026. The filing states Vanguard exercises sole dispositive power over 2,963,293 shares and has sole voting power for 16,109 shares and that these holdings include securities held for Vanguard funds and managed accounts.

Insights

Institutional Ownership Analyst

Vanguard holds a meaningful passive stake in Otter Tail Corp (7.06%).

Vanguard Portfolio Management reports beneficial ownership of 2,963,293 shares, with sole dispositive power over the full position and limited sole voting power of 16,109 shares. The filing is a Schedule 13G, indicating passive investment status under applicable rules.

Because the filing states holdings include shares held for Vanguard funds and managed accounts, trading activity will depend on those underlying portfolios rather than a single active decision-maker. Subsequent filings may show changes if positions are adjusted.

Regulatory Compliance Specialist

Filing follows 13G disclosure conventions and notes fiduciary/agency holdings.

The disclosure cites SEC Release No. 34-39538 language to explain that holdings reflect securities over which Vanguard exercises dispositive power on behalf of funds and managed accounts. It also confirms no other person holds >5% separate interest in the reported position.

Signature and filing details are provided, with the reporting person identified and a signature date of 04/29/2026. This aligns with passive investor reporting obligations under Schedule 13G.

Key Figures

Beneficial ownership: 2,963,293 shares Percent of class: 7.06% Sole voting power: 16,109 shares +2 more

5 metrics

Beneficial ownership 2,963,293 shares reported for period ended <date>03/31/2026</date>

Percent of class 7.06% percentage of common stock outstanding

Sole voting power 16,109 shares shares for which Vanguard has sole voting power

Sole dispositive power 2,963,293 shares shares for which Vanguard has sole power to dispose

CUSIP 689648103 Otter Tail Corp common stock identifier

Key Terms

Schedule 13G, Beneficial ownership, Sole Dispositive Power, CUSIP

4 terms

Schedule 13G regulatory

"This filing is a Schedule 13G reporting beneficial ownership"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

Beneficial ownership financial

"Amount beneficially owned: 2963293; Percent of class: 7.06 %"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

Sole Dispositive Power regulatory

"Sole power to dispose or to direct the disposition of: 2963293"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

CUSIP market

"CUSIP Number(s): 689648103"

A CUSIP is a nine-character alphanumeric code that uniquely identifies a U.S. or Canadian financial security—such as a stock, bond, or fund share—like a Social Security number for an investment. It matters to investors because brokers, exchanges and record-keepers use the CUSIP to match trades, track ownership, settle transactions and pull accurate records, reducing errors and ensuring money and securities go to the right place.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Otter Tail Corp

(Name of Issuer)

Common Stock

(Title of Class of Securities)

689648103

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 689648103

1

Names of Reporting Persons

Vanguard Portfolio Management

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

PENNSYLVANIA

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 16,109.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 2,963,293.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,963,293.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

7.06 %

12

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person: In accordance with SEC Release No. 34-39538 (January 12, 1998), this Schedule 13G reflects the securities beneficially owned, or deemed to be beneficially owned, by Vanguard Portfolio Management LLC and the following affiliates of Vanguard Portfolio Management LLC or business divisions of such affiliates: Vanguard Fiduciary Trust Company and Vanguard Global Advisers, LLC. This Schedule 13G includes securities held by Vanguard funds, or sleeves thereof, over which Vanguard Portfolio Management LLC exercises dispositive power, in addition to securities held by clients over which the affiliates or business divisions of such affiliates indicated above exercise dispositive and/or voting power. This Schedule 13G does not include securities, if any, beneficially owned by other subsidiaries or affiliates of Vanguard Portfolio Management LLC, or business divisions of such subsidiaries whose ownership of securities is disaggregated from that of the reporting business unit in accordance with such release.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Otter Tail Corp
(b)	Address of issuer's principal executive offices: 215 South Cascade Street, PO Box 496, Fergus Falls, MN, 56538
Item 2.
(a)	Name of person filing: Vanguard Portfolio Management
(b)	Address or principal business office or, if none, residence: 100 Vanguard Blvd,, Malvern, PA, 19355
(c)	Citizenship: PA
(d)	Title of class of securities: Common Stock
(e)	CUSIP Number(s): 689648103
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2963293
(b)	Percent of class: 7.06 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 16109
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 2963293
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. Vanguard Portfolio Management, including investment companies registered under the Investment Company Act of 1940 and other managed accounts, have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities reported herein.No one other person's interest in the securities reported herein is more than 5%.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Vanguard Portfolio Management

Signature:	Ashley Grim
Name/Title:	Head of Global Fund Administration
Date:	04/29/2026

FAQ

How many Otter Tail Corp (OTTR) shares does Vanguard Portfolio Management report owning?

Vanguard reports beneficial ownership of 2,963,293 shares, representing 7.06%. The Schedule 13G states Vanguard has sole dispositive power over those shares and sole voting power for 16,109 shares as of 03/31/2026.

Does Vanguard vote or control all the Otter Tail shares it reports?

Vanguard reports sole dispositive power over 2,963,293 shares but sole voting power for 16,109 shares. The filing explains many shares are held in Vanguard funds and managed accounts where voting or dispositive authority may be allocated across affiliates.

What does Schedule 13G indicate about Vanguard's intent toward OTTR stock?

A Schedule 13G filing typically signals passive investment intent rather than active solicitation. The filing identifies Vanguard as a passive holder under the 13G rules and uses release language describing holdings across funds and managed accounts.

Who signed the Schedule 13G filing for Vanguard and when was it signed?

The filing is signed by Ashley Grim, Head of Global Fund Administration. The signature line shows a signature date of 04/29/2026, with the reported ownership tied to the period ended 03/31/2026.